Many digital computers and in particular many personal computers are designed so that the same computer can accommodate a variety of memory sizes. These computers generally have a plurality of switches which must be set to designate the amount of memory which has been inserted in the system. Other computers have an electronic means for detecting how much memory has been inserted into the computer.
With existing systems, the memory chips (called DRAMS) must be inserted in sequential sections because the system determines how much memory the system has by checking the memory up to the point where it finds no chips at a particular location.
The DRAMS generally available come in a variety of sizes and configurations. For example, at the present time 256K and 1 Meg DRAMS are very common. Such DRAMS are generally available in configurations such as, for example, 256 by 1, or 256 by 4, etc.
In many existing digital computers, only certain size DRAMS can be inserted in certain memory banks. Each memory bank can only accommodate one size of DRAMS because either switches (or some other configuration mechanism) provides the starting address of each bank and the system assumes a particular size from that starting address. Other presently known systems include physical switches which indicate the size of the DRAMS in an associated memory bank. Such systems are relatively costly and inflexible.
Thus, present digital computers and in particular present personal computers have limitations on the flexibility of how various size DRAMS can be inserted in various memory banks.